1. Field of the Invention
The present invention relates to a waste toner container and an image forming apparatus, and more particularly to a waste toner container capable of stable and efficient toner concentration control and an image forming apparatus that incorporates the waste toner container.
2. Description of the Related Art
Background image forming apparatuses, such as printers, facsimiles, copiers, and multifunction apparatuses that print, facsimile copy, and so on, generally use an electrophotographic process for image forming. In the electrophotographic process, toner is used to form an image.
In the course of image formation, the transfer rate of the toner from source to image is not 100%, and therefore waste toner that is not used to form the image is generated. Typically, the waste toner is collected in a waste toner container provided in the image forming apparatus, after which the waste toner is then discarded.
In the waste toner container, a sensor such as a photointerrupter or the like is provided to detect the amount of toner in the waste toner container. Further, a container having a large capacity is usually employed for collecting the waste toner to prevent the waste toner from leaking out of the waste toner container. For achieving downsizing of the image forming apparatus using electrophotographic process, it is desirable to use more of the space inside the waste toner container to hold waste toner (hereinafter “utilization rate”) so as to be able to reduce the overall size of the waste toner container.
As for a procedure to increase the utilization rate of the waste toner in the waste toner container, a tall waste toner container having sufficient height is efficient insofar as the waste toner is accumulated therein in a vertical direction. However, due internal space constraints of a space of the image forming apparatus, it may be necessary to prepare a waste toner container having a flat shape.
Accordingly, various other attempts have been made to increase the utilization rate. For example, in an example image forming apparatus according to JP-H11-305623-A, the waste toner fed into a waste toner container through a toner entrance in the container is conveyed internally by a toner conveyance screw. When the waste toner container is filled with the waste toner, a toner amount detector detects a full-tank condition, i.e., that the waste toner container is filled with the waste container. Further, a shielding body is provided between a side of the toner entrance and a side of the toner amount detection part to avoid erroneous detection at the toner amount detection part even when the waste toner container is detached or inclined. JP-H11-305623-A further describes a mechanism that includes a conveyance direction switching point so as to change the waste toner conveyance direction by the toner conveyance screws in the waste toner container.
However, provision of the shielding body is provided in the container complicates the configuration of the waste toner container. In addition, the conveyance direction switching point is located directly under the toner entrance. Accordingly, the waste toner accumulates symmetrically thereat. As a result, the waste toner is detected when the waste toner is piled up to a height at which the toner amount detector is disposed, but leaving the space inside the container above the toner amount detector unused.